Trans pump gear tooth count. Would using a 12 tooth instead of a 11 tooth matter ?

SCHMITTY

SCHMITTY

Not enough time
Building a 47rh on a budget for a broke kid. He sheared the teeth off his inner pump gear somehow and gouged the pump body. I bought a 47rh pump used off eBay but after comparing them closer on the bench the outer gear has a different tooth count. The original outer gear also is a slightly larger diameter and wont fit in the eBay pump. The inner gears appear to have the same inside diameter where the converter slides in.

Anyone have any info on pump gears ?
 
48re pumps normally have 10 inner lobes. Some 47rh's also have 10 inner lobes. Every 47re pump came with 11 inner lobes. The 10 lobe setup flows more, and the 48re pump flows even more than the old 47rh pumps, that said, under 750 HP can be easily handled with a 47re 11 inner lobe setup.

I've seen core pumps/core transmissions come in with old 14 and 15 lobe setups that worked, I have no idea how much line pressure they would handle in the typical diesel RPM ranges.
 
Thanks Will. I don't think this truck will be making more than 300.

So a 47 rh pump can support more hp than a 47re ?
 
SCHMITTY said:
Thanks Will. I don't think this truck will be making more than 300.

So a 47 rh pump can support more hp than a 47re ?
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Yes, it seems like the old 47rh pumps, when in good condition, will flow more than a 47re pump. But a good condition 48re pump will outflow everything else we've tested.
 
I'd say no. Just from looking at the 47rh and 47re next to each other rh being the 10 tooth and re being the 11 tooth. The outer diameter of the pump gears is slightly different- the 10 tooth rh won't fit in the re pump. So I'd assume the 48 gears will be too large to fit in the 47 pump
 
How about a whole 48re pump on a RH housing? Just looking for what the best pump option for the RH would be as I will most likely be replacing mine.
 
biggy238 said:
Anyone know why the pumps changed lobe count anyway?

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Increased oil volume. The 10 lobe gear has a wider lobe diameter (each lobe of the gear vs. the 11 lobe pump). The 10 lobe gear also has a larger circumference so it is a larger gear set.



What you will really notice with this gear set is reduced pressure drops between shifts and especially TC lockup.
 
I meant why the switch FROM 10 to 11. I'm assuming pulse dampening.


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biggy238 said:
I meant why the switch FROM 10 to 11. I'm assuming pulse dampening.


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And I answered the question above. More volume.

To get more technical with you. When they redesigned the the 47re VB to what is now the 48re VB; increased internal boost pressures and the circuits that controlled them were increased. This increase in pressure needed and increase in volume to meet higher application pressure in 3rd and 4th gear(OD) and the boost circuit. It is known that as you increase pressure there are usually drops in volume (This right here can get super technical.... what pump, design perameters, ect... ect). I am sure this was done to combat the decrease in volume while they increased internal pressure in the VB itself.

Now.... this is taken from articles I read over the last few years as information on 48VB's that has been disseminated. if you search in the interwebs I am sure you you will find articles relating to 48 VB. Sonax, ATSG, and a few transmission publications. Disclaimer! I am no engineer but I have build a few hundred units in my time.

The 47RE and the 48re are very different VB in terms of internal design and the changes they made. Makes for interesting reading.
 
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raychem said:
And I answered the question above. More volume.

To get more technical with you. When they redesigned the the 47re VB to what is now the 48re VB; increased internal boost pressures and the circuits that controlled them were increased. This increase in pressure needed and increase in volume to meet higher application pressure in 3rd and 4th gear(OD) and the boost circuit. It is known that as you increase pressure there are usually drops in volume (This right here can get super technical.... what pump, design perameters, ect... ect). I am sure this was done to combat the decrease in volume while they increased internal pressure in the VB itself.

Now.... this is taken from articles I read over the last few years as information on 48VB's that has been disseminated. if you search in the interwebs I am sure you you will find articles relating to 48 VB. Sonax, ATSG, and a few transmission publications. Disclaimer! I am no engineer but I have build a few hundred units in my time.

The 47RE and the 48re are very different VB in terms of internal design and the changes they made. Makes for interesting reading.
Click to expand...
You did. I was backwards on my thoughts about pump displacement vs revs.

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